In this paper, a downlink cell-free massive multiple-input multiple-output (CF massive MIMO) system and a network clustering is considered. Closed form sum-rate expressions are derived for CF and the clustered CF (CLCF) networks where linear precoders included zero forcing (ZF) and minimum mean square error (MMSE) are implemented. An MMSE-based resource allocation technique with multiuser scheduling based on an enhanced greedy technique and power allocation based on the gradient descent (GD) method is proposed in the CLCF network to improve the system performance. Numerical results show that the proposed technique is superior to the existing approaches and the computational cost and the signaling load are essentially reduced in the CLCF network.

翻译：本文研究了下行无小区大规模多输入多输出（CF massive MIMO）系统及其网络聚类方法。推导了采用线性预编码器（包括迫零（ZF）和最小均方误差（MMSE））的CF网络与簇状CF（CLCF）网络的闭合形式总速率表达式。在CLCF网络中提出了一种基于MMSE的资源分配技术，该技术采用基于增强贪心算法的多用户调度以及基于梯度下降（GD）方法的功率分配，以提升系统性能。数值结果表明，所提技术优于现有方法，并且CLCF网络中的计算开销与信令负载得到了显著降低。